Mastering sudo: Essential Linux Privilege Tricks for Everyday Use

Linux’s sudo command lets regular users run selected root commands. Below are typical usage scenarios and tips.

Scenario 1: User lacks permission to run root commands

When a normal user needs root privileges, prefix the command with sudo. Before sudo existed, su was used, which required the root password. Permissions are defined in /etc/sudoers.

Granting a single user:

guohl – username allowed to use sudo

ALL – from any terminal

(ALL) – as any user

ALL – any command

To let user test run only /bin/chown and /bin/chmod on host guohl-pc as root:

Similarly, replace the username with %group to grant the rule to all members of a group (e.g., the sudo group).

Scenario 2: Forgot sudo while editing with vim

If you edit a file in vim and realize you lack permission to save, you can run: :w !sudo tee % This writes the file with root privileges without leaving the editor.

Scenario 3: Forgot sudo before a command

When a command fails due to missing privileges, instead of re‑typing it, simply execute: sudo !! Here !! expands to the previous command.

Scenario 4: Using sudo with shell built‑in commands

Shell built‑ins (e.g., cd, type) cannot be prefixed with sudo because sudo runs external programs. To run a built‑in as root, first obtain a root shell: sudo bash After entering the root shell, you can execute any command without additional sudo prefixes.

Scenario 5: sudo command logging

Administrators can record every command run via sudo, enhancing security and aiding troubleshooting. Basic logging configuration involves editing /etc/sudoers to enable log output.

References

sudo manual

7 Linux sudo Command Tips and Tricks

sudo logging configuration